The dynamic motion of \(\langle \bar{q}q \rangle \) 
will globally be processed instantaneously at \(T \sim 0.7 T_{\rm pc}\) . Since the scalar field \(\langle \bar{q}q \rangle \)  couples to
the meson and baryon states, the nonadiabatic particle production will then
take place and reheat the Universe from \(0.7 T_{\rm pc}\)  up to
\(T_{\rm reh} (< T_{\rm pc})\) .
The typical time scale of the dynamic \(\langle \bar{q}q \rangle \)  motion is much faster than the background Hubble evolution, as will be clarified later.
Hence the \(T\)  dependence is safely negligible until
the \(\langle \bar{q}q \rangle \)  motion ends to be trapped at the true vacuum.
This is the characteristic feature of the QCD preheating, in contrast to a class of the preheating scenarios at
higher scales (see, e.g., a review  [1]}, [2]}, [3]}, [4]}),
where the Hubble friction becomes crucial during the inflaton
oscillation.
This is how the QCD preheating works and can successfully
create the pions and nucleons through the nonperturbative and nonadiabatic processes, as will be explicitly seen below.
